Many of your metal materials do not look very realistic. When making metals, make sure you keep diffuse colors or textures very dark... almost black, or a very dark gray. And the more reflective metal material is, the higher Fresnel IOR you use... so for example 10-15 for chrome, 5-8 for brushed steel, 4-5 for aluminium, etc... :)
Using very low diffuse values, combined with high fresnel IOR numbers and not extreme reflective value... (for example i use reflectivity of just RGB 220 220 220 for chrome) will get you very realistic metal...
I am mentioning this especially because this is already second set of very well done and detailed scenes focused on metal materials that just miss right metal setup :)
